Eloquent Experiments Trivia Quiz

Answer: Microorganisms

The presence of tiny, tiny organisms in apparently clear lake water revolutionized our understanding: suddenly, it was apparent that a whole world was hidden from the naked eye. Van Leeuwenhoek (1632-1723) was not the inventor of the microscope, though his significant advances in lensmaking enabled his exciting discoveries.

He had a good instinct, too, for where to look: not only lake water, but also fossils, muscle tissue, and even human saliva. (Of that last sample, he wrote to the Royal Society in 1683, "Moreover, the other animalcules were in such enormous numbers, that all the water. . . seemed to be alive.")

Answer: Scurvy

Scurvy is a disease of malnutrition. Unlike many other animals, human beings can't synthesize Vitamin C, but we do need it in order to make collagen, which is a critical protein in our connective tissues. Without Vitamin C, scurvy slowly develops, beginning with lethargy and continuing on through even worse symptoms, including bleeding gums, jaundice, convulsions, and death. Over time, greens and citrus fruits -- rich in Vitamin C -- gained a reputation as folk remedies for scurvy, but huge numbers of sailors and travelers still died of the disease.

Lind (1716-1794) was the ship's doctor on the Salisbury when he took six pairs of sailors who were dying of scurvy, and added a different supplement to the diet of each pair -- a clinical trial of different remedies, and thus the forebear of modern medical research. The citrus fruits were the clear winner, although problems with cost and availability meant it would be decades more before citrus was routinely available to sailors.

Answer: Phlogiston

Before Lavoisier's work, chemists believed that rusting and burning came about when a sort of essence of fire -- phlogiston -- was released from the material in question into the air. The air, however, could support only a limited amount of phlogiston before becoming saturated, explaining why a fire in a closed vessel (with a limited amount of air) would die down before consuming all its fuel. Even the discoverer of oxygen, Joseph Priestley, subscribed to phlogiston theory, describing the gas as "dephlogisticated air" that was simply far away from its saturation point!

To disprove phlogiston theory once and for all took some impressive experiments. Lavoisier showed that air was a mixture of gases, one that supported burning and one that did not. (The first is what we now call oxygen; the second is actually a mixture of other gases, the most prominent being nitrogen.) By heating tin in a closed vessel until it formed an ashy residue called a calx, Lavoisier showed that the tin actually increased in mass -- not what you would expect if it were emitting phlogiston. He followed up by forming a mercury calx, and showing that the air remaining in the vessel did not contain any oxygen. Even better, when he heated the mercury calx still more, the original oxidation reaction reversed and it emitted oxygen -- in the exact amount that was missing from the first vessel. There was no way for phlogiston theory to explain that!

Answer: Electricity and magnetism

Oersted's experiment relied on a very simple circuit in which current, supplied by a battery, flowed through a wire. (The battery itself was a recent invention then, only twenty years old!) A compass needle, located by happenstance underneath the wire, rotated to point at a right angle to the wire when current was flowing. When the flow through the wire was reversed, the needle pointed the opposite way. And when the flow was stopped, the needle relaxed to its original orientation, pointing towards the north magnetic pole of the Earth.

We now know that electricity and magnetism are closely interrelated. Moving electrical charges, such as electrons flowing through a wire, produce a magnetic field; a changing magnetic field induces an electric field. Introductory physics students can tell you that you can predict the orientation of the compass's magnetic needle using the famous "right-hand rule". A current-carrying wire produces circular magnetic field lines around itself, perpendicular to the wire at every point. If you place your right hand around the wire so that your thumb points in the direction of the current flow, then the magnetic field lines point around the wire in the same sense that your fingers wrap around it.

Answer: Spontaneous generation

Spontaneous generation, the belief that some living organisms could spontaneously arise from non-living matter, was once a cornerstone of Western natural philosophy. Thinkers from the ancient Greeks forward proposed a whole biological universe of spontaneous generation -- maggots from meat, barnacles from rocks, fleas from dust, and crocodiles from sunlit mud. This may have been one of the most poetic scientific theories ever proposed, but we now know the idea was a real obstacle to public health.

Pasteur's takedown of the theory was anything but spontaneous. He carefully designed the swan necks of his flasks to ensure that air could flow in, but dust -- unaided by gravity and likely to adhere to the sides of the tubes -- could not. He hypothesized that microbes spread by hitching rides on airborne dust particles, so an intact neck would keep them from colonizing the sterilized contents of the flask. Pasteur was thrilled by the clear and eloquent results: "Never," he wrote, "will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment."

Answer: Garden pea plants

The choice of the garden pea was important for three reasons. First, it was easy for Mendel to control which plants bred with which; he could even breed some plants with themselves! Second, they breed fairly quickly, which is helpful for gathering data; Mendel could raise two generations of pea plants to adulthood every year. (Modern geneticists use even faster-breeding organisms, like fruit flies -- which only need two weeks from hatching to become parents themselves!) The second advantage of the garden pea is that the plant has several easily observed traits that don't have intermediate varieties. For example, the flower is always either purple or white, never lavender or pink; the stem is always either short or long, never in between. This simplified data collection and avoided confusion: the offspring's flower color would never be a blend of its parents.

In careful experiments and statistical analysis published in 1866, Mendel, a monk in what is now the Czech Republic, realized that these traits were inherited independently of each other (the Principle of Independent Assortment) and that each parent passed only one allele for each trait down to its offspring (the Principle of Segregation). (We would now describe an allele as a particular form or variant of the gene governing that trait.) The offspring's expression of the trait depends on the two alleles that it inherited from its parents. Mendel also realized the difference between dominant and recessive alleles, and even coined those terms. Although his work was largely unknown in his lifetime, it was rediscovered around 1900 and guided the development of the young science of genetics.

Answer: It was thought to be necessary to transmit light

By this time, light was known to be a type of wave -- an electromagnetic wave. (It's also a particle, of course, but that quantum mystery still lay in the future then.) Scientists were familiar with other kinds of waves, from surf to sound, and none of these waves could travel without a medium to support them. Think of a crowd of sports fans doing "the wave": the wave moves all the way around the stadium, supported by a medium of people who don't move much. Physicists assumed that light must also travel in a medium -- the luminiferous, or light-bearing, ether, which filled all space yet was so thin that planets, moons and stars never felt its drag.

Michelson and Morley used a device called an interferometer to look for the effect of the ether on the speed of light. If the Earth travels through ether on its way around the Sun, then light should travel a little faster in the downwind direction and a lot slower in the upwind direction. The experiment took light from a lamp, and split it into two paths, each with a mirror at the end. One path went along the Earth's direction of motion and back, while the other was perpendicular; the difference in the speed of light would be evident when the light from both paths was recombined after a round trip. The experimenters were careful and thorough; they even designed the system so that the whole thing could be rotated to any angle. But they didn't find any sign of ether.

Less than twenty years later, Albert Einstein's theory of special relativity provided another way to look at light, without the need for ether at all.

Answer: Atomic nuclei

We now know that an atom consists of negatively charged electrons orbiting around a very dense, positively charged nucleus, which is made in turn of positive protons and neutral neutrons. Most of the mass of an atom is located in the nucleus, but most of the volume is empty space. Before Rutherford's experiment it was thought that mass and charge were more evenly distributed in the volume of an atom, so they expected the dense alpha particles (a type of radiation that Rutherford had proven two years earlier were helium atoms with the electrons stripped away) to pass straight through the foil. Instead, they discovered that there was something inside the foil, even denser and heavier than an alpha particle. What's more, it was tiny; nothing else could explain how unlikely it was to be struck by an alpha.

The findings excited the scientific world, and within a decade the existence of positively charged atomic nuclei was widely accepted. Nuclear physics -- a blessing and a curse for humanity -- had been born.

Answer: X-rays

X-rays are a type of light with high energy and therefore short wavelengths. Scientists had been using them since the 1910s to probe crystal structures: since the wavelengths of X-rays are around the same size as the features of crystals, the rays form telltale interference patterns as they pass through. Franklin was an expert at X-ray diffraction, and her group became quite skilled at crystallizing DNA under various conditions and then probing it with X-rays. Franklin's famous "Photo 51," taken by a graduate student she was supervising, showed a clear and beautiful X shape with well-defined dark and light patches. The X shape was characteristic of a helix! Meanwhile, measuring the separation of the dark and light patches allowed scientists to calculate details of the structure, such as the pitch angle of the spiral and the length of the ladder rungs.

James Watson and Francis Crick, who went down in history as the discoverers of DNA's double-helix structure, relied on this photograph as they formulated their description of the molecule. (They were shown the photograph without Franklin's permission, kicking off a controversy that still raged more than sixty years later.) This one eloquent photograph was worth a thousand words, or at least a thousand base pairs.

Answer: The Big Bang

The Big Bang Theory says that the universe has not remained in some steady, constant state for all time. Instead, it began small, and dense, and hot, and rapidly expanded from there. (In fact, as astronomers have found, it's still expanding!) The noise that Penzias and Wilson saw was essentially leftover thermal radiation from a time when the universe was still quite young, about 380,000 years after it began.

It was very dense and hot compared with today, but in the intervening billions of years the radiation has cooled, just as the universe has. Now called the Cosmic Microwave Background Radiation, Penzias's and Wilson's noise is intensively studied by modern scientists, who use tiny variations in the signal to learn about the earliest structures in the universe.